The subject matter discussed in this section should not be assumed to be prior art merely as a result of its mention in this section. Similarly, a problem mentioned in this section or associated with the subject matter provided as background should not be assumed to have been previously recognized in the prior art. The subject matter in this section merely represents different approaches, which in and of themselves can also correspond to implementations of the claimed technology.
Users interact with a touch-screen user interface of a device with touch gestures. The device detects one or more touch events (e.g., tap, swipe, pinch-in, rotate, etc.) when the user performs a touch gesture on the touch screen using fingertips or other pointing devices. The device interprets the user's detected touch events. Detection and interpretation of a touch gesture can be well defined by the location and movement of the physical contact (or close proximity) between the user's fingertip(s) and the touch screen.
Interpreting a user's gestures in a three dimensional (3D) free space placed in front of a device is challenging as often there is no clear indication whether the user's gesture in the 3D free space engages the device. It is also challenging in determining a particular portion or a particular hierarchical level of a user interface that the user is interacting with using gestures in the 3D free space.